1. FIELD OF THE INVENTION
The present invention relates to an assembly to be fitted in a cylinder of a probe.
2. Prior Art
A touching needle is installed on an end of a cylinder through the medium of an insulating material. An assembly, which is formed by connecting an electric parts unit with a connecting portion for a coaxial cable, is inserted into the cylinder through the other end thereof.
An inserting end of the assembly is a lead projecting from the electric parts unit, or is a splitted end of a spring member soldered on the lead.
In a probe with a circuit for high and low impedance, a changeover switch is installed on a connecting part for a coaxial cable.
A receiving recess is formed on an inner end of the touching needle. A hole to be used for soldering is formed from the outer side surface of the needle to the receiveing recess. The lead or the spring member is inserted into the receiving recess, and is soldered on the touching needle by pouring solder through the hole.
In order to insert the lead or the spring member into the receiving recess which has a very small diameter, the axial line of the lead or the spring member has to be at one with the axial line of the receiving recess. The lead of the electric parts unit has, however, a very small diameter of about 0.4 mm, so that it is cuurved easily by external forces. Consequently, it is very difficult to care for the electric parts units not to be curved. To make matters worse, the cylinder is of metal and not transparent, so that only a skilled hand can insert the lead or the spring member into the receiving recess for a short time.
It is possible to recognize whether or not the lead is received in the recess only when the hole has a diameter more than 0.8 mm. Even when the hole has a large diameter, it is almost impossible to recognize whether or not soldering is complete by pulling back the assembly, as soldering becomes incomplete or is broken easily even by a weak shearing force, because soldering area is extermely small. Incomplete soldering causes incomplete conductibility.